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Building blocks of Earth 'present in every solar system'

The building blocks of planets like Earth are far more common than previously thought, a team of astronomers has suggested -- in fact, they might be found in every solar system in the galaxy.

A new study by Prof Brad Gibson, of the University of Hull, presented at the National Astronomy Meeting in Llandudno, suggests the chemicals and minerals of which Earth is constructed are actually ubiquitous.

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The Earth is made up of combinations of carbon, oxygen, magnesium and silicon, but the precise ratios of these can have profound impacts on whether a planet ends up with plate tectonics, a cool surface and -- ultimately -- life.

It had previously been thought most rocky planets were either similar to Earth, or had higher concentrations of carbon or silicon, the latter at the cost of magnesium. "Too much magnesium or too little silicon and your planet ends up having the wrong balance between minerals to form the type of rocks that make up the Earth's crust," said Gibson in a press statement. "Too much carbon and your rocky planet might turn out to be more like the graphite in your pencil than the surface of a planet like the Earth."

If the building blocks are there, then it's more likely that you will get Earth-like planets.Prof Brad Gibson

But after studying a new simulation of the Milky Way's chemical evolution, Gibson and his team found that instead of one-in-three solar systems having the right blend of elements, every solar system did. When they checked the model and the previous predictions they found the older science, not their work was at fault.

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"We couldn't find a fault with the model, so we went back and checked the observations. There we found some uncertainties that were causing the one-in-three result. Removing these, observations agreed with our predictions that the same elemental building blocks are found in every exoplanet system, wherever it is in the galaxy," said Gibson.

The results could mean a profound increase in the number of planets which could be capable of hosting life. But it doesn't mean every planet will look just like Earth -- in our own Solar System there are plenty of worlds with the same mix of elements but which for various reasons -- either their size, position in relation to the Sun or presence in the path of asteroids -- means they are not suitable for life.

Neither does this study make it particularly easy to find these worlds. While several space and ground-based telescopes are searching for exoplanets throughout the galaxy, the nature of that search -- which relies on noticing small shifts in light reaching us from very distant stars -- makes it difficult to find smaller worlds orbiting their stars at enough of a distance to be hospitable. "Even with the right chemical building blocks, not every planet will be just like Earth, and conditions allowing for liquid water to exist on the surface are needed for habitability [...] We only need to look to Mars and Venus to see how differently terrestrial planets can evolve," Gibson said. "However, if the building blocks are there, then it's more likely that you will get Earth-like planets -- and three times more likely than we'd previously thought."